Transmission mechanism having an automatic gear change system

ABSTRACT

Transmission mechanism having an automatic gear change system comprising an assembly of hydraulically controlled clutch and brake devices which include friction discs and hydraulic control cylinders supported by coaxial partly overlapping bell-shaped members whose concave sides face in the same axial direction. An end wall member has an outer periphery connected to rotate with the open end portion of the larger bell-shaped member and an inner periphery fixed to an element of a planetary gear train of the mechanism.

United States Patent [191 Piret June 26, 1973 I TRANSMISSION MECHANISMHAVING AN AUTOMATIC GEAR CHANGE SYSTEM [75] Inventor: JeanPiret,Bougival, France [73] Assignee: Automobiles Peugeot, Paris, RegieNationale Des Usines Renault, Billancourt, both of France [22] Filed:July 1, 1971 21 Appl.No.: 158,732

[30] Foreign Application Priority Data July 30, 1970 France 7028140 [52]U.S. Cl. 74/763 [51] Int. Cl. Fl6h 57/10 [58] Fieldoi Search 74/759,761, 763, 74/765, 732

[56] References Cited UNITED STATES PATENTS 3,554,057 l/l97l Michnay etal. 74/732 3,035,457 5/1962 Cartwright 74/763 3,049,945 8/1962 Lindsay74/759 3,053,115 9/1962 Cartwright et a] 74/763 Primary ExaminerArthurT. Mel (eon Assistant Examiner-Gregory LaPointe Attorney-Burns, Doane,Swecker & Mathis 57] ABSTRACT Transmission mechanism having an automaticgear change system comprising an assembly of hydraulically controlledclutch and brake devices which include friction discs and hydrauliccontrol cylinders supported by coaxial partly overlapping bell-shapedmembers whose concave sides face in the same axial direction. An endwall member has an outer periphery connected to rotate with the open endportion of the larger bell-shaped member and an inner periphery fixed toan element of a planetary gear train of the mechanism.

7 Claims, 2 Drawing Figures TRANSMISSION MECHANISM HAVING AN AUTOMATICGEAR CHANGE SYSTEM The present invention relates to transmissionmechanisms having an automatic gear change system, in particular forautomobile vehicles.

Such mechanisms are known which are disposed between an output shaft andan input shaft and comprise a planetary gear train and hydraulicallycontrol brake and clutch devices whose selective actuation determinesthe value of the transmission or gear ratio of the mechanism. Thepresent invention relates to such a mechanism specifically arranged inthe following manner. The planetary gear train comprises two sun gearsrespectively integral with two coaxial shaft portions. The first of thesun gears is connected to the input shaft through a first clutch havingfriction discs, the second sun gear being rendered integral with anintermediate element capable of being connected through a second clutchto the input shaft and through a brake to the casing of the mechanism.Generally, the input shaft carries a bell-shaped'member connected bysplines to a series of discs of the first clutch and by other splinestoa series of discs of the second clutch whereas said intermediateelement is a second bell-shaped member fixed to the second shaft portionand connected by splines to the other series of discs of the secondclutch and by other splines to a series of discs of the brake whoseother series is integral with the casing. It should be mentioned thatthe expression splines must be understood to designate broadly anysuitable means for interconnectin g two members to rotate together whileallowing axial movement therebetween. Each clutch device or brake deviceis actuated hydraulically by a piston and cylinder device preferably ofannular shape, the cylinder and the actuating chamber of each clutchbeing defined by a portion of the corresponding bell-shaped member.

A more complete description of such a mechanism is given in-the FrenchPat. Applns. No. 70 03 902 filed on Feb. 4, 1970, and 70 23 348 filed onJune 24, 1970, filed by the Applicants. In these patents, the twobellshaped members have their concave ends facing each other, thebell-shaped member of smaller diameter being integral with the inputshaft. They generally have a U-shaped diametral section which results ina number of drawbacks The bell-shaped member of larger diameter has aroughly flat end wall which partly defines the receiving chamber for thehydraulic fluid controlling the second clutch and it has been found thatit is imperfectly adapted to resist the pressure forces and liable tobecome deformed, which adversely affects the performance of themechanism. Two arrangements which might be adopted for remedying thisdrawback and which consist either in decreasing the diameter of theouter bell-shaped member or imparting thereto a different shape moresuitable for withstanding the forces due to the pressure, are notentirely satisfactory. The first-mentioned arrangement results in adecrease in the diameter of the clutch discs and consequently requires agreater number of discs for a given torque. The second arrangementresults in a large increase in the axial size of the mechanism, which isunacceptable in the design of modern vehicles and in particular invehicles having a transverse engine unit.

Another serious drawback of the aforementioned known mechanism resultsfrom the fact that the same intermediate element, namely the outerbell-shaped member, is subjected to, on one hand, as indicatedhereinbefore, forces due to the presence of the hydraulic fluid underpressure, and, on the other hand, the forces due to the transmission ofthe torque, so that there results in the region of the connection byradial interengagement or splines of the bell-shaped member to theintermediate shaft portion, a composition of stresses which isparticularly detrimental to the correct performance of the member.

An object of the invention is to remedy these various drawbacks.

The invention provides a transmission mechanism having an automatic gearchange system comprising an input shaft, an output shaft, a planetarygear train, an

assembly of hydraulically controlled clutch and brake devices,comprising two bell-shaped members acting as supports for friction discsand hydraulic control cylinders, said two members being coaxial andpartly overlapping, wherein said two members have their concave sidesfacing in the same direction and there is provided an end wall memberconnected to rotate on its outer periphery with the open end of thebell-shaped member of larger diameter and on its inner periphery with anelement of the planetary gear train.

With this arrangement it is possible, among other things, to give to theend portion of the outer bellshaped member such shape as to enable it toresist the pressure forces, this shape being, for example, frustoconicalor stepped without increasing the axial overall size, since thebell-shaped member of smaller diameter or inner member is disposedentirely within the outer member. Further, there is a separation of thefunctions, since the forces due to the torque are transmittedessentially by the end wall member and no longer by the end wall portionof the bell-shaped member.

Further features and advantages of the invention will be apparent fromthe ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a side elevational view, partly in section, of an automaticgear change mechanism to which the invention is applied, and

FIG. 2 is a partial sectional view of a modification of the mechanismaccording to the invention.

FIG. 1 shows a transmission mechanism having an automatic gear changesystem arranged in accordance with the invention. This mechanism willnot be described in detail only the parts thereof necessary for anunderstanding of the present invention will be described.

The mechanism is disposed in a casing C and comprises the following mainsub-assemblies an input shaft 1, an output shaft 2 carrying a pinion 3adapted to mesh with a differential crownwheel (not shown), a planetarygear train P, two clutches E E two brakes F F and a free-wheel mechanismR.

Secured to the input shaft 1, for example by welding or electronicbombardment, is a bell-shaped member 4 more precisely having a U-shapeddiametral section and comprising an end wall portions 5 and a lateralwall portion 6. Formed in the lateral wall 6 are inner splines 7 onwhich are mounted discs 10 disposed between two plates 8, 9. The discs10 are discs of 'a first series of discs. These discs and plates areretained by a ring 11. A sleeve 12 attached to the lateral wall 6 in thevicinity of the end wall portion 5 defines a cylinder in which isslidably mounted a piston 13 which is axially guided by the shaft 1. Adiaphragm spring 14 biases the piston 13 in a direction away from theplate 8. The bell-shaped member 4 and the piston 13 define a chamber 15which can be supplied with fluid under pressure by way of a connection16 and conduits 17, 18 and 19. A second series of discs 20, inalternating relation with discs 10, is connected to rotate with a layshaft 21 carrying a first sun gear P of the planetary gear train P. Theassembly just described constitutes the clutch E The input shaft 1 isrotatably mounted in a sleeve 22 having an outer radial shoulder 23 towhich is secured, for example by welding, a bell-shaped member 24. Thelatter practically surrounds the member 4 and has an end wall portion 25which is roughly frusto-conical and a cylindrical lateral wall portion26 which has slidably mounted therein a piston 27 which is axiallyguided by the sleeve 22 and biased by a diaphragm spring 28. This pistonand the bell-shaped member 24 define a chamber 29 which is supplied withfluid under pressure by way of a connection 30 and conduits 31, 32 and33. The cylindrical lateral wall portion 26 of the bellshaped member 24has splines 34 on which are mounted discs 37 disposed between two plates35, 36. The discs 37 alternate with discs 38 which are connected torotate with the inner bell-shaped member 4. This assembly constitutesthe clutch E,.

On the splined portion 34 of the bell-shaped member 24 there is alsomounted an end wall member 39 of pressed sheet metal which is retained,in the same way as the plates 35, 36 and the discs 37, by a spacermember 40 and a ring 41. The end wall member 39 is welded on its innerperiphery, for example by electronic bombardment, to a hollow shaft 42which is rotatably mounted on the shaft 21 and carries a second sun gearP of the planetary gear train P. It will be understood that the end wallmember 39 can be connected to the shaft 42 in any manner, for example bysplines.

It will be observed that the hub 43 of the free-wheel mechanism R isrotatably mounted on the hollow shaft 42. This hub is moreover connectedby teeth means to the planet gear carrier 44 of the planetary geartrain. A washer 45 carrying an element 46 having antifriction propertiesis connected by tabs 47 to the hub 43, the element 46 being in contactwith the adjacent end wall member 39. The outer ring 48 of thefree-wheel R is integral with an annular member 49 secured to the casingC.

It is unnecessary to describe in detail the operation of the mechanismwhich is conventional. However, owing to the particular arrangement ofthe bell-shaped members 4, 24, whose concave sides face in the samedirection, particularly interesting results are obtained. Thus it ispossible to give to the end wall portion 27 of the bell-shaped member 24a frustoconical shape which imparts thereto an improved resistance tothe forces created by the admission of fluid under pressure into thechamber 29 which precludes any deformation liable to affect the correctoperation of the mechanism. Further, in the region of its connection tothe sleeve 22, that is, on its inner periphery, the member 24 transmitsno torque and no stress composition is produced in this region as inconventional arrangements. The torque transmitting force is supported bythe end wall member 39 which has a shape specially designed therefor.The member 39, on the other hand, is subjected to no force discs 37 and38 a sufiicient radial extent so that there' is no need to increase thenumber of these discs and the axial overall size.

It will also be observed that the connections 16 and 30 are connected tothe respective chambers l5and 29 in a particularly simple manner by wayof the input shaft 1. r

The embodiment shown in FIG. 2 differs from the embodiment shown in FIG.1 only in respect of the shape of the inner bell-shaped member 4 andouter bell-shaped member 24 and the shape of the end wall member 39 andthe casing C. The members 4 and 24 have a stepped shape so as to permitthe provision of a recess 50 in the casing to clear the startergearwheel 51. The pistons 13 and 27 are correspondingly modified.

As concerns the end wall member 39", it is of pressed metal and has arecess 52 into which extends the free edge of the bell-shaped member 4.This enables the overall length of the mechanism to be slightly reduced.

As an additional modification, the end wall member 39 or 39 may beconnected to the bell-shaped member 24 by welding it to the plate 35 or35' instead of being retained by a ring as shown in the drawing. 7

It should be also mentioned that other modifications may be made in thismechanism without departing from the scope of the invention. Inparticular, the hubof the free-wheel R may be welded to the planet gearcarrier of the planetary gear train. Further, this train may be of atype other than that illustrated.

Having now described my invention what I claim and desire to secure byLetters Patent is l. A transmission mechanism having an automatic gearchange system, comprising a casing, and mounted in the casing an inputshaft, an output shaft,a planetary gear train having two sun gears, setsof planet gears carried on one planet carrier and one ring geardri-vingly connected to the output shaft, an assembly of hydraulicallycontrolled clutch and brake devices, which include two bell-shapedmembers and friction discs and hydraulic control cylinders supported bythe bellshaped members, said two members being in coaxial and in partlyoverlapping relation to each other, one of said members being largerthan and outside the other member, said two members having concave sidesfacing in the same direction, the larger outer bell-shaped member havingan inner wall portion remote from an open end portion and secured to asleeve which is rotatably mounted on the input shaft, the innerbell-shaped member having an inner wall portion remote from said openend portion and secured to the input shaft, a hub member located insidesaid inner bell-shaped member and connected to rotate with anintermediate shaft having splined thereon a first of said sun gears, ahollow shaft rotatable on said intermediate shaft and having splinedthereon a second of said sun gears, a free-wheel device located aroundsaid hollow shaft and in a space defined between said clutch and brakeassembly and having a hub member rotatably mounted on said hollow shaftand connected to rotate with said planet carrier and an end wall memberhaving an outer peripheral portion connected to rotate with said openend portion of the larger bell-shaped member and an inner peripheralportion connected to rotate with said hollow shaft.

2. A mechanism as claimed in claim 1, wherein the larger outerbell-shaped'member has an end wall portion which is remote from saidopen end portion and has a frusto-conical shape.

3. A mechanism as claimed in claim 1, wherein the larger outerbell-shaped member has an end wall portion which is remote from saidopen end portion and has a stepped shape, the casing having a shapesimilar to the stepped shape so as to permit clearing an element outsidethe casing.

4. A mechanism as claimed in claim 1, 1, wherein the freewheel devicehub is combined with an antifriction element which is in contact with anadjacent face of the I end wall member.

5. A mechanism as claimed in claim 1, wherein the end wall member hasnotching on said outer peripheral portion engaged with splines on thelarger outer bellshaped member and retained by a resiliently yieldablering.

6. A mechanism as claimed in claim 1, wherein the outer peripheralportion of the end wall member is welded to a clutch plate which isconnected to rotate with the larger outer bell-shaped member.

7. A mechanism as claimed in claim 4, wherein the end wall member is ofpressed sheet metal and has an axially offset portion into which anouter edge of said other bell-shaped member extends.

1. A transmission mechanism having an automatic gear change system,comprising a casing, and mounted in the casing : an input shaft, anoutput shaft, a planetary gear train having two sun gears, sets ofplanet gears carried on one planet carrier and one ring gear drivinglyconnected to the output shaft, an assembly of hydraulically controlledclutch and brake devices, which include two bell-shaped members andfriction discs and hydraulic control cylinders supported by thebell-shaped members, said two members being in coaxial and in partlyoverlapping relation to each other, one of said members being largerthan and outside the other member, said two members having concave sidesfacing in the same direction, the larger outer bell-shaped member havingan inner wall portion remote from an open end portion and secured to asleeve which is rotatably mounted on the input shaft, the innerbell-shaped member having an inner wall portion remote from said openend portion and secured to the input shaft, a hub member located insidesaid inner bell-shaped member and connected to rotate with anintermediate shaft having splined thereon a first of said sun gears, ahollow shaft rotatable on said intermediate shaft and having splinedthereon a second of said sun gears, a free-wheel device located aroundsaid hollow shaft and in a space defined between said clutch and brakeassembly and having a hub member rotatably mounted on said hollow shaftand connected to rotate with said planet carrier and an end wall memberhaving an outer peripheral portion connected to rotate with said openend portion of the larger bell-shaped member and an inner peripheralportion connected to rotate with said hollow shaft.
 2. A mechanism asclaimed in claim 1, wherein the larger outer bell-shaped member has anend wall portion which is remote from said open end portion and has afrusto-conical shape.
 3. A mechanism as claimed in claim 1, wherein thelarger outer bell-shaped member has an end wall portion which is remotefrom said open end portion and has a stepped shape, the casing having ashape similar to the stepped shape so as to permit clearing an elementoutside the casing.
 4. A mechanism as claimed in claim 1, 1, wherein thefreewheel device hub is combined with an antifriction element which isin contact with an adjacent face of the end wall member.
 5. A mechanismas claimed in claim 1, wherein the end wall member has notching on saidouter peripheral portion engaged with splines on the larger outerbell-shaped member and retained by a resIliently yieldable ring.
 6. Amechanism as claimed in claim 1, wherein the outer peripheral portion ofthe end wall member is welded to a clutch plate which is connected torotate with the larger outer bell-shaped member.
 7. A mechanism asclaimed in claim 4, wherein the end wall member is of pressed sheetmetal and has an axially offset portion into which an outer edge of saidother bell-shaped member extends.